According to sources, Maron would be portraying an agent on De Niro’s talk show who plays a part in booking Phoenix’s character, eventually causing him to go mad and become the Clown Prince of Crime.

Phillips will co-write and direct the Warner Bros. movie, which is set to bow on Oct. 4, 2019.

Insiders stress that Jared Leto, who starred as the Joker in “Suicide Squad,” is still on board to portray the character in the DC Universe and that this Phoenix pic has no effect on what happens with Leto’s character in future DC films. Leto will star in his own standalone Joker movie.

Maron was most recently seen as television director Sam Sylvia on the Netflix comedy “Glow,” earning the actor some of the best reviews of his career. He is repped by ICM Partners and Avalon Management.